Hazrat Ali (radhiyallahu ‘anhu) reports that Rasulullah (sallallahu ‘alaihi wasallam) said, “When a person makes miswaak and then stands to perform salaah, an angel stands behind him and listens attentively to his recitation of the Qur’aan. The angel then draws close to him until it places its mouth upon his mouth. Whatever portion of the Qur’aan he then recites is protected in the belly of the angel (and thereafter secured by Allah Ta‘ala). Hence, ensure that you cleanse your mouth before reciting the Qur’aan.”